In a dental treatment, a desired treatment may be performed by cutting a surface layer of a tooth. A medical cutting tool used during the treatment includes a shank portion gripped by a chuck of a handpiece, and a working portion continuously formed from the shank portion and including a cutting blade which is formed from an outer circumference to a leading end portion and is used to cut a surface layer. The medical cutting tool formed as described above is fixed to the handpiece when the shank portion is gripped by the chuck. Then, by an operation of a doctor, the rotating working portion is pressed to a portion to be treated, thereby cutting a desired portion.
In the medical cutting tool, the working portion needs to ensure a sufficient cutting performance with respect to a hard surface layer. Thus, in general, the working portion is formed using cemented carbide represented by tungsten carbide. The shank portion needs to ensure strength that can sufficiently resist bending and warping affected when a desired portion is cut by the working portion. When the working portion is formed using cemented carbide to improve the strength of the shank portion, it is preferable that the shank portion be formed continuously from the working portion and using cemented carbide.
However, there occurs a problem that the time used to process the cemented carbide in a shape corresponding to the medical cutting tool takes long. Thus, the shank portion is formed using, for example, SUS 420 which is martensitic stainless steel or carbon tool steels (SK), an intermediate component used to form the working portion is formed by cemented carbide, and the intermediate component of the working portion is bonded to a leading end of the shank portion by pressure welding, so that a medical cutting tool processed in a desired shape is provided.
As described above, when stainless steel or tool steel and cemented carbide are bonded to each other, an optimum method corresponding to a material to be bonded is selected and employed from methods such as pressure welding including friction pressure welding and heating pressure welding, resistance welding, and brazing in general.